Getting the timers up and running properly will always mean more money, and won't turn any buyers off - worthwhile investment for the non-runner as not everyone will want to buy a project.

The restore side though is a personal aesthetic choice. Here you might put some buyers off even with a sympathetic relume, as they will take a lot of wear and patina for the sake of originality. When looking to sell, I think it's always safest to leave that decision to the buyer once bought - it's up to them then. Someone who wants it to look pristine can have the work done, the others can leave it original. The second choice isn't possible if you restore prior to selling.